In the first stanza of Section 54, Tennyson comments on how we have to blindly accept that good will triumph over evil, even though people do not always act with good intentions.

Oh, yet we trust that somehow good

Will be the final end of ill,

To pangs of nature, sins of will,

Defects of doubt, and taints of blood;

There is evil in the world, but we have to trust that good will win in the end.

Tennyson's efforts to explore faith in "In Memoriam" allow him to develop the idea of spiritual conflict at length. As humans, we have to be like babies, blindly accepting that we are going to be taken care of and that there is a higher power that knows what's good for us.